Fastener driving tool



April 2, 1968 R. F. NO'VAK ET Al. 3,375,758

FASTENER DRIVING TOOL Filed Sept. 13, 1966 C5 Sheets-Sheet 'i FI G. I

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FASTENER DRIVING TOOL I Filed sept. 13, 196e 5 Sheets-Sheet K w. m ,a w K P MO@ m mm QH V O A W T o m NR A FF. NN B DDM w WR MA YW W .A O RH N9 M [o: o 7 @Q N/Z VO- M OQ wv Y Y B @OE April 2, 1968 R. F. NOVAK ET A1. 3,375,758

VFASIENER DRIVING TOOL Filed Sept. 13, 1966 5 Sheets-Sheet 3 FIGS.

INVENTORS: RAYMOND F. NOVAK HOWARD B. RAMSPECK BY ,mmf/d ATT'YS United States Patent O 3,375,758 FASTENER DRIVING TOOL Raymond F. Novak and Howard B. Ramspeck, Chicago, Ill., assignors to Fastener Corporation, Franklin Park, Ill., a corporation of Illinois Filed Sept. 13, 1966, Ser. No. 579,085 7 Claims. (Cl. 91-356) ABSTRACT OF THE DISCLOSURE A pneumatically operated fastener driving tool is provided with suitable control mechanism to provide for single-cycle operation. The improved control mechanism may be applied to a known type of tool wherein a drive or power piston is slideably mounted in the cylinder of the tool. A control valve is provided which is actuated by depression of a trigger or other manual actuator to control the movement of .the drive piston through a drive stroke, and thereafter automatically and sequentially to return the drive piston through a return stroke. The control valve is connected -between the main valve controlling the iow of fluid to the cylinder, and receives a signal when the -drive piston is at the end of its drive stroke to reeondition the cylinder for the return stroke of the piston.

This invention relates to a fastener driving tool and, more particularly, to a fastener driving tool including new and improved control means, and to control means for a fastener driving tool.

Commercial pneumatic fastener Vdrivin-g tools on the market today are generally -of the type operated by a trigger actuated pilot valve that functions when the trgger is depressed to move the drive piston and connected `fastener driving blade through a power or drive stro-ke of a fastener driving operation by admission of pressurized iiuid into ythe cylinder of the tool. The drive piston will generallyfremain at the end of its power stroke until the fluid pressure in the cylinder is released, as by exhausting the cylinder to the atmosphere, at which time the piston return means is effective to return the piston 'to its normal or static position. Moreover pneumatic fastener driving tools are known wherein the drive piston and driving blade move both down and up automatically upon depression of the trigger, before the trigger is released. For example, one such tool is described and claimed in a copending application of Howard B. Ramspeck, Ser. No. 457,767, filed May 21, 1965, which application is assigned to the same assignee as the present invention. This snap-action or automatic single cycle piston and driving blade operation is desirable in many applications such as upholstery stapling to prevent fraying of the material by the driving blade while the tool is moved along the workpiece.

Accordingly, one object of the present invention is to provide a new and improved snap-acting pneumatically actuated fastener driving tool. n

Another object of the present invention is to provide a fastener driving apparatus including new and improved single-cycle control means for automatically and sequentially returning the drive piston and driver blade after completion of the fastener driving operation.

Yet another object of the present invention is to provide ya new and improved pneumatically actuated fastener driving tool'.

Yet a further object of the present invention is the provision of a new and improved control valve for a fastener driving t-ool which is effective to cycle the drive piston and driver blade through the power and return strokes automatically upon depression of the trigger.

3,375,758 Patented Apr. 2 1968 Yet a further object of the present invention is to provide a fastener driving apparatus having a new and improved control valve which automatically and sequentially effects connection of the main cylinder rst to a fluid reservoir and then to the atmosphere without the necessity of releasing the trigger.

In accordance with these and many other objects, there is provided a new and improved single-cycle control valve fora pneumatically opera-ted fastener driving tool. The improved control valve may be applied to a known type of tool provided with a housing having a cavity defining a fluid reservoir, and having a main cylinder in the housing. A drive or power pist-on is slideably mounted in the cylinder and is actuated in its drive stroke by the communication of one end of the main cylinder with the fluid reservoir and is thereafter automatically 4driveny one end of the cylinder through a main valve which mayy be a diaphragm-type poppet valve of the type described in detail in Patent No. 3,208,356 granted Sept. 28, 1965 to O. A. Wandel. A trigger pilot valve is provided for controlling the poppet valve. t

In accordance withy the present invention, the new and improved control valve is connected between the main valve and the trigger pilot valve to control the snap-acting motion of the fastener driving tool. The new and improved single-cycle control valve includes a valve body defining a valve cylinder having stepped diameters to provide at least a large diameter cylinder contiguously connected to a small diameter cylinder. A valve element is slideable in the cylinder and includes a small piston in the small diameter cylinder and a large piston in the large diameter cylinder. A first port in the end of the small cylinder beyond the stroke of the small piston is vented to the atmosphere. 4A second port communicating with the valve cylinder adjacent the step therein between the stroke of the large and small pistons is connected to the liuid reservoir. A third port,` which may be -in the form of a plurality of radial ports, is provided in the large diameter cylinder intermediate the stroke of the large piston and is connectedto .the poppet valve. Yet a fourth port extends from the end of the large cylinder beyond the stroke of the large piston 'connected to the trigger pilot valve. f i

1 When the fastener driving tool is static, or at regt, pressurized fluid from the fluid reservoir passes through the triggerpilot valve, through the control valve, and to the main valve to maintain the main valve closed. However once the trigger pilot valve is depressed, the fluid Afrom above the main valve is exhausted through the control valve and the trigger pilot valve to the atmosphere, thereby initiating the driving stroke of the` drive piston. The

differential pressure acting on the valve element will move the valve element, at a rate dependent on the relative size of the large and small cylinders, so as to drive the large piston past the ports connected to the main valve and thereby connecting the fluid reservoir with the main valve to close the main valve and to return the drive piston through its return stroke. Release of the trigger will return the valve`element of the control valve to its static or at rest position so that the pressurized fluid from the uid reservoir then passes through the trigger pilot valve, control valve and to the main valve tomaintain the main valve in its closed position.

In accordance with another feature of the present invention, the control valve is readily adapted to a fastener driving tool of the type wherein pressurized fluid from the fluid reservoir is directly connected to the underside of the piston to initiate the return stroke of the piston. To this end, the single-cycle control valve described above additionally includes an additional stepped diameter portion defining an exhaust cylinder contiguous with the large diameter cylinder on the side thereof remote from the small diameter cylinder. The valve element includes a portion extending into the exhaust cylinder with spaced third and fourth pistons thereon slideably received within the exhaust cylinder. Port means are provided in the exhaust cylinder between the strokes of the pistons connected directly to the fluid reservoir. Additional port means communicating with the lower side of the drive piston are provided in the exhaust cylinder intermediate the stroke of the fourth piston. Additional means at the end of the exhaust cylinder connect the exhaust cylinder to atmosphere.

This latter embodiment of the single-cycle control valve, in addition to functioning as described above, further vents the underneath of the drive piston to the atmosphere during the driving stroke, and thereafter automatically and sequentially connects the fluid reservoir to the underside of the drive piston to return the drive piston to its static or at rest position.

Many other objects and advantages of the present invention will become apparent from considering the following detailed descriptions in conjunction with the drawings in which:

FIG. 1 is a fragmentary cross sectional view of a fastener driving tool incorporating the improved single-cycle control valve according to the present invention and illustrated with the drive piston and driver blade in its static or at rest position;

FIG. 2 is a fragmentary cross sectional view of the fastener driving tool of FIG. 1, illustrated with the drive piston and driver blade completing the drive stroke;

FIG. 3 is a fragmentary cross sectional view of the fastener driving tool of FIG. 1, illustrated with the drive piston and driver blade completing its return stroke prior to the release of the trigger pilot valve;

FIG. 4 is a cross sectional detail view taken along line 4-4 of FIG. 1;

FIG. 5 is a fragmentary cross sectional view of the control valve mechanism of the fastener driving tool of FIG. 1, drawn to a larger scale, and illustrated in a static or at rest position;

FIG. 6 is a fragmentary cross sectional view of the control mechanism of FIG. 5, illustrated during the driving stroke;

FIG. 7 is a fragmentary cross sectional view of the control mechanism of FIG. 5, illustrated during the return stroke of the drive piston and driver blade prior to the release of the trigger pilot valve;

FIG. 8 is a fragmentary cross sectional view of a modified fastener driving tool incorporating an improved single-cycle control valve according to the present invention having an additional feature and illustrated with the drive piston and driver blade during the driving stroke thereof; and

FIG. 9 is a fragmentary cross sectional view of the fastener driving tool of FIG. 8, illustrated with the drive piston and driver blade in its return stroke prior to the release of the trigger pilot valve.

Referring now to the drawings, there is fragmentarily illustrated a fastener driving tool, generally illustrated as 10, which embodies the present invention. The tool 10 may be of known construction and, as illustrated, comprises a housing 12 including a generally vertically extending head or forward portion 12a and a rearwardly extending hollow handle portion 12b defining a fluid reservoir 16. Pressurized fluid, such as compressed air, is supplied to the fluid reservoir 16 of the tool by a suitable flexible line. The drive system for the tool 10 includes a main or power cylinder 18 mounted within the head portion 12a and having an open upper end 18a thatA is adapted to be selectively connected to the reservoir 16. The open upper end of the cylinder 18 is normally in engagement with a diaphragm-type main or cylinder valve assembly 20, here shown of the poppet type, under the control of a safety or touch-trip valve assembly 22, a trigger pilot valve assembly 24, both of known design, and a snap-acting or single-cycle control valve assembly 25 according to the present invention. A fastener driving assembly 27 includes a power or drive piston 26 slideably mounted within the cylinder 18 having connected thereto a depending driver blade member 28. The driving blade assembly 27 is normally biased to a position with the piston 26 adjacent the main valve 20. An exhaust valve assembly indicated generally as 32 is provided for controlling the selective connection of the upper end of the cylinder 18 to the atmosphere.

When the tool 10 is to be operated, the safety valve assembly 22 and the trigger pilot valve assembly 24 are Iclosed so that compressed fluid from the reservoir 16 enters the upper end of the cylinder 18 and drives the yfastener driving assembly 27 downwardly to engage and set a fastener or nail supplied to a drive track 36 in a nosepiece or nosepiece structure 38. The flow of cornpressed fluid into the upper end of the cylinder 18 is controlled by the main valve assembly 20, which includes a diaphragm 40, the periphery of which is clamped between a cap 42 and the head portion 12a of the housing 12 and which seats against the upper edge 18a of the cylinder 18. The diaphragm 40` is resiliently biased against the upper edge surface 18a by a spring 44 located between the cap 42 and the diaphragm 40. The cylinder side of the diaphragm 40 is continuously in communication with the fluid reservoir 16 through a suitable passageway 46 so that pressurized fluid continuously acts :against the cylinder side of the diaphragm 40 tending to displace the diaphragm 40 from the edge 18a of the cylinder 18. However pressurized fluid is also introduced to the opposite sides of the diaphragm 40 through a passageway 48 when the fastener driving tool 10 is in a static or at rest position. The differential pressure acting on the diaphragm 40 is effective to maintain the diaphragm 40 in a closed position, as illustrated in FIG. 1. However, if the pressurized fluid above the diaphragm 40 is discharged, the pressurized fluid acting through passageway 46 is effective to unseat the diaphragm 40 from the edge 18a of the cylinder 18 to dump pressurized fluid into the top of the main cylinder 18 and to drive the drive piston 26 through a drive stroke.

When the fastener driving tool is at rest, or during the return stroke of the drive piston, the upper open end of the cylinder 18 is exhausted to the atmosphere through the exhaust valve assembly 32. In the illustrated embodiment the exhaust valve assembly comprises a hollow valve stem 50` secured to the diaphragm and connecting the upper end of the cylinder 18 to atmosphere through a suitable exhaust passageway 52. However when the drive piston is operated through a fired or drive stroke, it is necessary for the upper end of the cylinder 18 to be closed, and to this end there is provided a valve seat 54 disposed adjacent the end of the valve stem 5-0 remote from the cylinder 18 and adapted to be engaged 'by the valve stem 50 when the diaphragm 40 is raised at the initiation of a drive stroke, thereby closing off the upper end of the cylinder 18 to the atmosphere.

To provide for the return drive of the fastener driving assembly 27, there is provided an air return chamber 60 communicating with the lower end of the cylinder 18 through a plurality o-f ports 62. Moreover the drive piston 26 is provided with suitable one way valve means to provide pressurized fluid to the air return chamber 60 during the driving stroke thereof. To this end, the piston 26 is provided with a suitable groove 64 in its side wall containing a suitable sealing means such as the O-ring 66. A suitable recess 68, best illustrated in FIG. 4, defines a iiuid bypass around the O-ring 66 as the piston moves through its drive stroke. More specifically, when the pressure above the piston 26 is greater than the pressure in the cylinder 18 below the piston 26, the O-ring 66 will be driven against the bottom of the groove 64, permitting a blowby or bypass of pressurized iiuid through the recess 68. This bypass of pressurized fluid will pass through the port 62 into the air return chamber 60 to provide pnessurized fluid for the return of the piston 26 to its static position. Once the main valve assembly 20 has closed to cut olf the pressurized uid from above the piston 26 and to exhaust the cylinder 18 above the piston 26 to the atmosphere through the exahuast valve assembly 32, the O-ring 66 will be driven against the top edge of the g-roove 64 to provide a positive seal. At that time the pressurized Huid in the air return chamber 60 will return the piston 26 to its static position. Subsequent thereto, there is suicient leakage around the driver blade 28 so that the pressurized fluid below the piston 26 will leak to atmosphere thereby preparing the tool for the next fastener driving operation.

Referring now to FIGS. 5, 6, and 7, there is illustrated the improved single cycle control valve assembly 25 shown in conjunction with the safety valve assembly 22 and the trigger pilot assembly 24. It will be understood, of course, that the control valve assembly 25 is equally applicable to a fastener driving tool which is not provided with the safety valve assembly 22. However, referring to the illustrated embodiment, it will be understood that the safety valve assembly 22 includes a valve stern 70 having a notched or recessed diameter portion 70a adjacent its upper 'end which is slidably received within a sleeve 72 to define a valve chamber 74 closed at its ends. A first port 76 is provided in the valve chamber 74 in communication with the safety valve assembly 22 and which is normally in communication with the reservoir 16 through a reservoir port 78. When the tool 10 is moved into engagement with the workpiece, the valve stem 70l is moved upwardly so that the upper end of the stern 70 closes off the reservoir port 78 and thereby closes off direct cornmunication between the reservoir p-ort 78 and the port 76. The same movement of the valve stem 70, however, places the port 76 in communication with a -pilot valve port 80.

The trigger pilot valve assembly 24 is of known design and includes a valve chamber 84 having opposed valve ports 86 and 88 defining valve seats alternately engageable by a valve element here illustrated as a ball valve 90. The valve port 86 communicates between the valve chamber 84 and the reservoir 16, while the valve port 88 exhausts the valve chamber 84 to the atmosphere when the ball valve 90 is unseated therefrom. To actuate the 'ball valve 90, there is provided a suitable rod actuator 92 operated by a suitable trigger 94 (FIGS. l, 2, and 3) so that when the fastener driving tool is at rest, the yball valve 90 is seated against the valve port '88, and when the trigger 94 is depressed, the ball valve 90 closes the valve port 86. Additionally the pilot valve port 80 on the safety valve assembly 22 communicates with the valve chamber 84 intermediate its length through a port 96. It will be understood that in the operation of the trigger pilot valve wnen the trigger 94 is released the port 96 is in communication with the reservoir 16 through the valve port 86; but when the trigger 94 is depressed unseating the ball from the valve port 88 and closing the valve port 86, the port 96 is exhausted to the atmosphere.

Referring now to the improved control valve in accordance with the present invention, the valve 25 includes a valve cylinder 100 having `a stepped portion to provide a large diameter cylinder 102 and a Small diameter cylinder 104. Slidably positioned within the valve cylinder 100 is a valve element 106. A -lirst O-ring 108 on the valve element 106 defines a small piston slideably received Within the small diameter cylinder 104 and a second 'O-ring 110 on the portion of the valve element 106 slideably received within the large diameter cylinder 102 defines a large piston. A first port 112 near the end of the small diameter cylinder 104 beyond the stroke of the `small piston 108 defines a vent port venting the small dia-meter cylinder 104 to the atmosphere. A second port 11-4 communicates between the reservoir 16 and the portion of the valve cylinder adjacent the step therein so as to open between the strokes of the pistons 108 and 110. A third port here shown as a plurality of radial ports 116` in the valve cylinder 100 p0- sitioned intermediate the stroke of the large piston 110 connects Iwith the passageway 48. Yet an additional port 118 beyond the travel of the large piston 110 communicates with the port 76 in the safety valve assembly 22 to provide a connection between the safety valve assembly 22 and the control valve assembly 25.

Fromy the above brief description of the invention the operation thereof is believed clea-r. However, brietiy, it will be understood that the single cycle control valve 25 is op` erated in series with the main valve 20. Fluidized pressure to control the main valve 20 passes through the control valve 25; likewise air bled from the main valve 20 also bleeds the air from under the large diameter piston 110 of the control valve 25. More specifically, referring to FIGS. 1 and 5, it wil-l be understood that when the fastener driving tool 10 is static or at rest, and the valve stem 70 is not in engagement with the workpiece, pressurized fluid will be directed above the diaphragm 40 of the main valve assembly 20 to hold the main valve assembly closed by passing through the port 78 into the valve chamber 74, through the port 76 and into the large diameter cylinder 102 of the control valve 25, then passing through the ports 116 and the passageway 48 to the main valve assembly 20. Engagement of the valve stem 70 with the workpiece changes the source of pressurized fluid from the port 78 through the valve port 86 of the trigger pilot valve, but does not alfect the pressure loading on the main valve assembly 20.

To lire the tool 10, the trigger 94 is depressed so that the reservoir 16 is shut 01T, and the pressurized fluid above the main valve assembly 20 is exhausted to atmosphere first through the passageway 48 and the ports 116, then through the ports 118` and the port 76 into the safety valve assembly, then through the port 80 of the safety valve assembly and the port 96 of the trigger pilot valve assembly to be exhausted through the valve port 88. This exhaust of air from above the main valve assembly 20 is effective to cause the diaphragm 40 to snap upwardly, dumping the air from the .reservoir 16 intol the upper end of the cylinder 18 above the piston 26 and driving the piston 26 through a power stroke. Simultaneously with the driving of the piston 26, the valve element 106 in the control valve 25 is driven downwardly, .a-t a rate dependent on the differential diameter-s between the large an-d small pistons 110 `and 108, as indicated in FIGS. 2 and 6. At the same time it will be understood that pressurized fluid which bypasses around the O-ring 66 of the piston 26 through the recess 68 will build up into a pressurized uid in the air return chamber 60 so as to provide a return force for the piston 26.

To provide a snap action return of the piston 26 and driver blade 28 sequentially upon its reaching the bottom of its drive stroke, the valve element 106 of the control valve assembly 25 will reach the bottom of its stroke where the piston 110 passes over the port 116 thereby closing ot further exhaust of pressurized fluid from above the main valve assembly 20, as indicated in FIGS. 3 and 7, and connecting the top of the main valve assembly in communication with the reservoir 16 through the passageway 48, port 116, valve cylinder 100, and the second port 114. This will close the diaphragm 40 against the upper edge 18a of the power cylinder and simultaneously will exhaust the upper end of the cylinder 18 to the atmosphere through the exhaust valve assembly 32, causing the pressurized iiuid in the air return chamber 60 to return the piston 26 to its static or at rest position.

As soon as the trigger 94 is released, the ball valve 90 will reseat itself against the valve port 88 and the pressurized fiuid .against the top of the diaphragm 40 is maintained either through the port 78 when the valve stem 70 is not depressed, or through the valve port 86 and the trigger pilot valve 24 when the valve stem 70 is depressed by engagement with a workpiece.

As previously indicated, the safety valve assembly 25 may be adapted to various types of poppet valves and return mechanisms. Moreover the control valve 25 may be used with or without the safety valve 22. The embodiment of the invention illustrated in FIGS. 8 and 9 illustrates a modified form of snap-acting control valve 126 applied to a modified form of fastener driving tool 128 having a different type of piston return arrangement. Since the fastener driving tool 128 in many respects is similar to the fastener driving tool 10 heretofore described, similar parts of both fastener driving tools will be represented by the same reference numerals.

Referring now to the embodiment of FIGS. 8 and 9, there is illustrated .a Afastener driving tool 128 including a housing 130. The housing 130 is provided with a forward vertical head portion 130a and a rearward or handle portion 13011 defining a fiuid reservoir 132. As heretofore described, the head portion 130a contains the main cylinder 18 having its upper end closed by the main valve assembly 20. The conventional trigger pilot valve assembly 24 is provided for initiating the power stroke of the tool 128. As heretofore described, the fastener driving assembly 27, including the drive piston 26 .and the driver` blade 28 are slideably mounted within the power cylinder 18. The exhaust valve assembly 32 provides for controlling the exhaust of the upper end of the cylinder 18 to the atmosphere.

The main valve assembly controls the power stroke of the fastener driving assembly 27 in like manner as heretofore described. More specifically the main valve assembly 20 includes the diaphragm 40 having its peripheral edges clamped between the cap 42 and the edge of the head portion 130e of the housing 130. Moreover the diaphragm 40 closes against the upper edge `18a ofthe cylinder 18 when the tool 128 is in the static position. The diaphragm 40 is urged to the closed position by the spring 44. The passageway 46 connects the underside of the diaphragm 40 with the fiuid reservoir 132. An additional passageway 48 connects the upper side of the diaphragm 40 with the control valve 126 according to the present invention. Moreover it is understood that the exhaust valve assembly 32 includes the hollow valve stem 50 which communicates with the atmosphere through an exhaust passageway 52 in the cap 42 of the t-ool 128. As heretofore described the hollow valve stem 50 is seatable against the valve seat 54 when the diaphragm 40 is raised off the edge 18a of the cylinder 18 to close the exhause valve assembly 32.

To provide for the return force of the fastener driving assembly 27, and to exhaust the air from below the drive piston 26 during the driving stroke, the lower end of the main cylinder 18 is provided with a plurality of ports 134 communicating with the control valve 126. During the driving stroke of the fastener driving assembly 27, fluid from below the drive piston 26 is exhausted to atmosphere through the exhaust ports 134 and control valve v126. Upon completion of the stroke of both fastener driving assembly 27 and control valve assembly 126 the exhaust ports 134 admit pressurized fiuid from the reservoir 132 yto provide for the return stroke of the drive piston 26.

Referring now to the control valve assembly 126 according to the present invention, the control valve assembly 126 is similar to the control valve assembly 25 heretofore described, but with an additional chamber and elongated stem to provide for exhaust and lcontrol of pressurized fluid below the drive piston 26. Accordingly, there is provided a valve cylinder 136 having the large diameter cylinder 102 and the small diameter cylinder 104 as heretofore described, and additionally provided with an additional stepped diameter portion defining a small exhaust cylinder 138 contiguous with the large diameter cylinder 102 and, in the illustrated embodiment, on the side thereof remote from the small diameter cylinder 104. As the control element of the control valve assembly I126, there is provided a modified valve element 140, similar in some respects to the valve element 106 in that it is provided with an O-ring 108 defining a small piston slideably received within the small diameter cylinder 104, and is further provided with the O-ring 110 defining the large piston slideably received within the large diameter cylinder 102. Additionally the valve element has a portion extending into the exhaust cylinder and provided with a pair of spaced O-rings 142 and 144 each defining a piston slideably received within the exhaust cylinder 138. In like manner as heretofore described in connection with the embodiment of FIGS. l through 7, the control valve assembly 128 is provided with the liirst or vent port 112 adjacent the closed end of its small cylinder 102, beyond the stroke of the small piston 108 and is provided with an additional port 114 communicating directly with the fiuid reservoir 132 and intermediate the length of the strokes of the pistons 108 and 110, and additionally the third port 116 connects the passageway 48 with the large diameter cylinder 102 intermediate the length of the stroke of the piston 110, while the fourth port 118 connects the end of the large diameter cylinder 102 to the valve chamber 84 in the trigger pilot valve assembly 24. In addition to the ports heretofore described, the exhaust cylinder 138 contains a fifth port 146 in communication with the fluid reservoir 132 and extending from the side wall of the exhaust cylinder 138 intermediate the strokes of the respective pistons 142 and 144. Additionally a sixth Iport 148 cornrnunicates with the lower end of the power cylinder 18 through the exhaust ports 134 therein and extends through the side wall of the exhaust cylinder 138 intermediate -the length of the stroke of the end piston 144. The lower end of the exhaust cylinder 138 defines an additional port exhausted to the atmosphere.

For controlling the operation of the tool 128, there is provided the trigger pilot valve assembly 24 in like manner as that heretofore described in the embodiment of FIGS. l through 7 and including the valve chamber 84 defining a valve port 86 in communication with the fluid reservoir 132 and an additional valve port 88 exhausting to atmosphere. A ball valve is alternately seatable against the valve ports 86 and 88 in response to movement by an actuator 92 upon depression or release of the trigger 94. The additional port 96 extends from the valve chamber 84 intermediate the movement of the ball valve 90 and communicates with the end of the large diameter cylinder 102 through the port 118.

In view of the above Idetailed description of the improved fastener driving tool 128, its operation is believed clear. However, briefly, it will .be understood that `the operation of the fastener drivng tool 128 is similar to that of the fastener drivng tool 10 described in the embodiments of FIGS. l through 7, except for the method of piston return and the exhaust of the cylinder 18a below the piston 26 during the power or drivng stroke. Accordingly, only this aspect of the fastener driving tool 128 is herein further described. As is herein apparent, driving of the piston 26 through its 4power or drive stroke is effective to exhaust the fluid from below lthe piston 26 through the exhaust ports 134 in the cylinder 18, through the port 148 into the exhaust cylinder 138 of the control valve assembly 126 and to atmosphere `through the port 150 thereof. However, as the piston 26 reaches the lower end of its stroke, the piston 144 passes over the opening of the ports 148 in the exhaust cylinder 138, thereby closing the exhaust ports 148 from communication with the atmosphere and connecting the exhaust ports 14S to the fluid reservoir 132 -through the ports 146. Pressurized fluid will now enter through the ports 146, pass through the body of the exhaust cylinder 138 and into the port 148 to be directed ythrough the exhaust ports 134 in the lower end of lthe power cylinder 18 to return the piston 26 upwardly toits static or at rest position.

Advantageously the embodiment of FIGS. 8 and 9 eliminates the air return chamber of the drive system thereby permitting for a small and more compact tool. Moreover there is a slight increase in the drive power by eliminating the air cushion which necessarily builds up under the drive piston during the drive stroke. The rapid return of the driver blade permits movement of the gun across fabric or other work surface without the danger of having the driver catch and snag the material. Moreover there may be provided a greater driver blade protrusion in the fired position, allowing for a fastener to be driven flush into a workpiece without applying pressure to the gun and with a very minimum of recoil.

Although the present invention has been described by reference to several embodiments thereof, it will be apparent that numerous other modifications and embodimen-ts mayV be devised lby those skilled in the art and it is intended by the appended claims to cover all modifications and embodiments which will `fall within the true spirit and scope of the present invention.

What is claimed `as new and desired to be secured by Letters Patent of the United States is:

1. A pneumatically operated fastener driving tool comprising a housing having a cavity defining a iluid reservoir, a cylinder in said housing, a piston slideably mounted in said cylinder, diaphragm valve engaging one end of said cylinder for controlling the admission of fluid to and the exhaustion of fluid from said one end of the cylinder, control valve means connected to said daphragm valve automatically operable upon initiation through a single-cycle for controlling the position of said diaphragm valve means to automatically and sequentially cycle said diaphragm valve first to open to connect said one end of the cylinder to the reservoir and thereafter to automatically exhaust said one end of the cylinder, and pilot valve means for initiating the operation of said cycle of said control valve means.

2. A pneumatically operated fastener driving tool comprising a housing having a cavity defining a fluid reservoir, a main cylinder in said housing, and a drive piston in said cylinder, cylinder valve means for controlling the admission and exhaust to said one end of said cylinder, single-cycle control val-ve means connected to said cylinder valve means automatically controlling the position of said cylinder valve means to sequentially cycle said cylinder valve means first to open to connect said one end of said main cylinder to the said reservoir and thereafter to exhaust said one end of said main cylinder, said control valve including a valve body defining a valve cylinder having stepped diameters to provide a large diameter cylinder contiguously connected to a small diameter cylinder, a valve element slideable in said valve cylinder and including first means defining small piston means in said small diameter cylinder and second means defining large piston means in said large diameter cylinder, first port means in the end of said small cylinder remote from said large cylinder and vented to the atmosphere, second port means adjacent the stepped portion of said control valve intermediate the strokes of said pistons communicating with said fluid reservoir, third port means in said large diameter cylinder intermediate the stroke of said large piston means communicating with said cylinder valve means, and fourth port means in the end of said large cylinder remote from said small cylinder, and pilot valve means connected to the last mentioned port means for initiating the operation of said control valve and adapted sequentially to connect said last mentioned port means first to the fluid reservoir 10 and, upon actuation, to exhaust said last mentioned port to the atmosphere.

3. A pneumatically operated fastener driving tool as set forth in claim 2 above wherein said cylinder valve means includes a diaphragm means extending across said one end of said main cylinder having one side thereof engageable with said main cylinder controlling the flow of .fluid into said one end and having the periphery of said one side of said diaphragm exposed to fluid from said fluid reservoir, and said cylinder valve means further including a hollow valve stem secured to said diaphragm and connecting said one end of lsaid cylinder to the atmosphere, and a valve seat disposed adjacent the end of said valve stem remote from said cylinder adapted to be engaged by the valve stem when the diaphragm is released to close off said one end of said cylinder, and wherein said third port of said control valve means is connected to the other side of said diaphragm means so that upon exhaust of said one other of said diaphragm means, said diaphragm raises off said one end of said power cylinder to admit pressurized fluid from said reservoir into said one end of said cylinder, and subsequent admission of pressurized fluid to said other side of said diaphragm means is effective to sequentially exhaust the fluid from said one end of said cylinder to permit said power piston to return to its at rest position.

4. A pneumatically operated fastener driving tool as set forth in claim 2 above wherein said main cylinder includes exhaust port means adjacent its other end, and wherein said control valve additionally includes an additional stepped diameter portion defining an exhaust cylinder contiguous with said valve cylinder, and said valve element extends into said exhaust cylinder, and wherein said valve element is provided with third and fourth means defining third and fourth spacedl piston means, said exhaust cylinder being provided with a fifth port means intermediate the length of the strokes of said third and fourth piston means `and communicating with said fluid reservoir, and wherein said exhaust cylinder is provided with sixth port means communicating with said exhaust port means in said other end of said main cylinder and communicating with the exhaustcylinder intermediate the stroke of said fourth piston, and wherein the end of said exhaust cylinder beyond the stroke of siad fourth piston means is provided vwith additional port means exhausting to the atmosphere.

5. A pneumatically operated fastener driving tool comprising a housing having a cavity ldefining a fluid reservoir, a cylinder in said housing, a piston slideably mounted in said cylinder, cylinder valve means for controlling the admission of fluid to and the exhaustion of fluid from one end of the cylinder and held closed by the pressure of fluid from said reservoir acting against one surface thereof and is opened by the exhaust of fluid from said one surface, control valve means connected to said cylinder valve means automatically controlling the position of said cylinder valve means to sequentially cycle said cylinder valve means first to open to connect said one end of the cylinder to the reservoir and thereafter to exhaust said one end of the cylinder, and pilot valve means for initiating the operation of said control valve means.

6. A pneumatically operated fastener driving tool comprising a housing having a cavity defining a fluid reservoir, a cylinder in said housing, a piston slideably mounted in said cylinder, cylinder valve means for controlling the admission of fluid to and the exhaustion of fluid from one end of the cylinder, said cylinder valve means including ldiaphragm means extending across said one end of said cylinder having one side thereof engageable with said cylinder controlling the flow of fluid into said one end and having the periphery of said one side of said diaphragm exposed to fluid from said fluid reservoir and further including a hollow valve stem secured to said diaphragm and connecting said one end of said cylinder to atmosphere, and a valve seat disposed adjacent the end of said valve stem remote from said cylinder adapted to be engaged by the valve stem when the diaphragm is raised to close off said one end of said cylinder, control valvemeans connected to said cylinder valve means automatically controlling the position of said cylinder valve means to sequentially cycle said cylinder valve means first to open to connect said one end of the cylinder to the reservoir and thereafter to exhaust said one end of the cylinder, and pilot valve means for initiating the operation of said control valve means, said control valve means being connected to admit pressurized uid from said reservoir to the other side of said diaphragm means and upon actuation of said pilot valve means to automatically and sequentialy first exhaust the fluid from said other side of saiddiaphragm means and thereafter to connect said other side of said diaphragm means to said uid reservoir to cycle said power piston through a drivingand return stroke.

7. A pneumatically operated fastener driving tool comprising a housing having a cavity dening a uid reservoira cylinder in said housing, a piston slideably mounted in said cylinder, cylinder valve means for controlling the admission of fluid to and the exhaustion of fluid from one end of the cylinder, control valve means connected to said cylinder valve means automaticallyv controlling the position of said cylinder valve means to sequentially cycle said cylinder valve means lrst to Open to c0nnect said one end of the cylinder to the reservoir and thereafter to exhaust said one end of the cylinder, and pilot valve means for initiating the operation of said control valve means, said control valve being further connected sequentially to exhaust said cylinder below said piston to the atmosphere, and thereafter automatically and sequentially to connect said lower end of said cylinder to the uid reservoir to provide the power for the return stroke of the piston.

References Cited UNITED STATES PATENTS 2,960,067 11/1960I Osborne. 3,106,134 10/ 1963 Osborne 91-461 3,112,489 12/1963 Beckman et al 9l--4l7 3,313,213 4/1967 Wandel 91--461 FOREIGN PATENTS 915,858v 1/19'63 Great Britain.

MARTIN P. SCHWADRON, Primary Examiner.

PA-UL E. MASLOUSKY, Examiner. 

